Can a circumcision be done wrong?

Definitely. As with any surgical procedure, things can always go wrong such as bleeding, infection, scarring, etc. Even if the procedure is done perfectly, there are patient medical conditions that may not allow optimal wound healing such as the ones listed above.
Circumcision . It is surgery on the penis. Technique and healing are both important factors in a nice outcome. Urologists are the experts.
Unfortunately. It is possible for too much or too little skin to be removed. Also for more skin off on one side or from top or bottom compared to other side causing curvature upwaerds, downwards or sideways. Occasionally a slice of glans is removed at tip of penis. Post cicumcision bleeding can cause a large hematoma or aslo significant bleeding. Very rare cases of partial amputation &/or cautery injury.